1. Field of the Invention
The present invention is related to a data transmission terminal apparatus, a data communicating method, and a data communication system, capable of transmitting, for instance, data via a wireless telephone line of a portable telephone to a communication counter party such as a data acquisition center.
2. Description of the Related Art
In general, in a data communication with employment of a wireless telephone line of a portable telephone, a modem is used. To execute such a data communication with using the modem, after a voice (speech) communication line for a telephone is linked, a negotiation for communicating data is carried out, so that a data communication link must be formed. That is, FIG. 1 shows a sequence diagram in the case that a data communication is carried out by issuing a telephone call from a portable terminal. As indicated in FIG. 1, the portable terminal first issues a telephone call to a counter party of this data communication so as to form a telephone communication link. Next, the portable terminal sends out a data communication request in order to execute the data communication via the modem, and makes a negotiation between the own portable terminal and the modem of the communication counter party so as to form a data communication link. After this data communication link has been formed, the data communication can be carried out between the portable terminal and the communication counter party via both the modems thereof.
As explained above, in the conventional data communication with employment of the wireless line of the portable telephone, after the telephone communication link has been established, the negotiation must be made between the modems of both sides in order to perform the data communication. To establish such a negotiation, several tens of seconds of negotiation time are required. As a result, even when information having such a small data capacity actually constituted by approximately 20 numerals is data-transmitted, for example, latitude/longitude information of positional information about the portable terminal side, such a lengthy time period of several tens of seconds to 1 minute is necessarily required. This conventional data communication system owns the problems as to the communication cost (communication fee) and the power consumption.
For example, in such an assumption case that while the conventional data transmission system is provided with a vehicle and an aged person who loiters from place to place without having his clear intention, the data transmission system automatically transmits positional information at proper timing, the following aspects are important view points. That is, the power consumption of this conventional data transmission system is reduced as much as possible, and this data transmission system can be driven by batteries as long as being permitted.
To reduce such redundant setting time, one solution method has been proposed. That is, the communication negotiation time with respect to the counter party, whose communication condition is previously set, is omitted by using the call issuer number notification so as to shorten the entire communication time, resulting in a reduction of communication fee.
This conventional data communication method may have a merit when an electronic mail is transmitted/received under stationary condition of a moving object. However, since the data is communicated in the non-sequential manner in this conventional method, for instance, in such a case that the data communication is carried out while a vehicle is driven in a high speed, if the wireless channels of the base stations are frequently switched, the following problem will occur. That is, even under such a better environment that the voice communication itself could be made in better electric field strength, the communication errors occur many times.
To avoid such a problem, the error correction and also the retry process which have been originally established in the layer lower than the transport layer of the telephone communication level of the digital portable telephone network must be newly executed in the application layer. That is, duplicate process operation is required in such a way that the error correction and the retry process are again established on the data communication transport layer. As a result, the communication time becomes redundant, and the overall system becomes complex.
The present invention has been made to solve the above-described various problems, and therefore, has an object to provide a data transmission terminal apparatus and a data transmission method, capable of transmitting data at a high speed under low power consumption.
To achieve the above described object, a data transmission terminal apparatus, according to an aspect of the present invention, includes:
a data transmission terminal apparatus including a portable type wireless telephone terminal, and a terminal control apparatus connected to the wireless telephone terminal, for performing a data communication by using a line of the portable type wireless telephone terminal; and
a data acquisition apparatus for communicating the data with the data transmission terminal apparatus; wherein:
in such a case that a telephone communication line of the portable type wireless telephone terminal is formed between the data transmission terminal apparatus and the data acquisition apparatus while involving a public telephone network, since the data transmission terminal apparatus sends out data as a dial signal from the terminal control apparatus via the wireless telephone terminal to the telephone communication line, the data is received in the form of a DTMF signal by the counter part of the data communication.
In accordance with the data transmission terminal apparatus of the present invention, after the telephone communication link is formed, the data is sent out as the dial signal. As a result, the data communication link is no longer formed, and therefore, the data can be transmitted to the counter party via the telephone communication line. Then, the counter party receives the data as the DTMF tone to decode this received data, and can readily demodulate the data.
As a consequence, the negotiation for the data communication link in the related art is no longer required in the data transmission terminal apparatus, so that the communication cost can be reduced and furthermore the power consumption can be lowered.